Process for preparing 5 8-dimethyl-5 6 7 8-tetrahydro-1-naphthols

ABSTRACT

5,8-DIMETHYL-5,6,7,8-TETRAHYDRO-1-NAPHTHOLS ARE PREPARED BY REACTING 1,5-HEXADIENE WITH A SUBSTITUTED OR UNSUBSTITUTED PHENOL IN THE PRESENCE OF A TRIPHENOXY ALUMINUM CATALYST. THE NAPHTHOLS CAN BE CONVERTED TO THE CORRESPONDING N-SUBSTITUTED CARBAMATES BY REACTION WITH AN ISOCYANATE. THE CARAMATES ARE USEFUL AS INSECTICIDES, MITICIDES, AND NEMATOCIDES.

United States Patent Ofiice 3,629,337 Patented Dec. 21, 1971 ABSTRACT OF THE DISCLOSURE 5,8-dimethyl-5,6,7,S-tetrahydro-l-naphthols are prepared by reacting 1,5-hexadiene with a substituted or unsubstituted phenol in the presence of a triphenoxy aluminum catalyst. The naphthols can be converted to the corresponding N-substituted carbamates by reaction with an isocyanate. The carbamates are useful as insecticides, miticides, and nematocides.

BACKGROUND OF THE INVENTION This invention relates to a process for preparing 5,8- dimethyl-S,6,7,8-tetrahydro-l-naphthols.

The preparation of tetrahydronaphthol derivatives by reacting a 1,5-hexadiene with either substituted or unsubstituted phenol is disclosed in an article by Bruson and Kroeger appearing in volume 62 of The Journal of the American Chemical Society at page 36. The authors coined the term cyclialkylation to describe this type of reaction. According to the article, the reaction of phenol with 2,5-dimethyl-l,S-hexadiene in the presence of anhydrous aluminum chloride produces 5,5,8,8-tetramethyl- 5,6,7,S-tetrahydro-Z-naphthol. The article further indicates that neither the corresponding l-naphthol isomer nor open chain monoalkylation products are obtained. Furthermore, although aluminum chloride is the classical example of a Friedel-Crafts type catalyst, when the reaction was repeated using other Friedel-Crafts type catalysts, viz, sulfuric acid and boron trifluoride, a hydroxyindane derivative was obtained rather than the tetramethyltetrahydronaphthol.

British Patent 706,425 discloses that the reaction of phenol with 2,5-dimethyl-l,S-hexadiene in the presence of boron trifluoride-glacial acetic acid catalyst produces only open chain alkylation products and no naphthol derivatives.

The reaction of p-cresol with 1,5-hexadiene in the presence of ZnCl or C H OSO H, which are also Friedel- Crafts type catalysts, to produce a 1:1 mixture of 4- methyl-2-(l-hexen-5-yl)phenol and 4,5,8-trimethyltetrahydro-l-naphthol is reported in a note appearing in Chemical Abstracts, volume 65, 8802a.

No utility is disclosed in either the Bruson and Kroeger article or the Chemical Abstracts note for the tetrahydronaphthols described therein.

It is an object of this invention to provide an improved method for preparing 5,8-dimethyl-5,6,7,S-tetrahydronaphthols.

SUMMARY OF THE INVENTION In accordance with this invention, 5,8-dimethyl-5,6,7,8- tetrahydro-l-naphthols having the formula OH CH;

wherein X and Y independently occupy the 2,3, or 4 positions and are independently selected from the group consisting of hydrogen, fluorine, chlorine, bromine, lower, alkoxy and lower alkyl, are prepared by reacting 1,5- hexadiene with a phenolic reactant having the formula wherein X and Y have the meanings given above, in the presence of an aluminum phenate (triphenoxy aluminum) catalyst. If X or Y is lower alkoxy, the other substituent is preferably hydrogen; if X or Y is fluoride, chloride, or bromine, the other substituent is preferably hydrogen or a like halogen; and if X or Y is lower alkyl, the other substituent is preferably hydrogen or lower alkyl. The terms lower alkoxy and lower alkyl refer to such groups having from 1 to 4 carbon atoms.

The reaction can be carried out at temperatures ranging from about C. to about 250 C., with the preferred temperature range being from about 160 C. to about 230 C.

The reaction proceeds readily at atmospheric pressure, but pressures above or below atmospheric can be used if desired.

The reactants can be added to the reaction mixture in any desired ratio, but normally it is desirable to employ an excess of the phenolic reactant. If desired, an inert solvent, such as chlorobenzene or nitrobenzene, can also be added to the reaction mixture.

The weight ratio of catalyst to 1,5-hexadiene can be from about 1:100 to about 1:05, with the preferred ratio being from about 1:10 to about 1:1.

The aluminum phenate catalyst can be prepared in situ by heating a suspension of aluminum and the phenolic reactant to be employed to between about C. and about 200 C. until hydrogen evolution has ceased. Alternatively, the aluminum phenate catalyst can be prepared beforehand from the same or different phenolic reactant and stored prior to use. As used herein and in the appended claims, the term aluminum phenate" includes aluminum phenates derived from phenolic reactants having the formula wherein X and Y are as defined herein.

The use of aluminum phenate as catalyst in the process of this invention offers several advantages over the use of other possible catalysts. The catalyst is relatively inexpensive, can readily be prepared in situ, and affords a high yield of the desired 5,8-dimethyl-5,6,7,8-tetrahydrol-naphthol reaction product.

The naphthols of this invention can be converted to the corresponding N-substituted carbamates, which are useful as pesticides, by reaction with an isocyanate of the formula RNCO wherein R is an alkyl or phenyl radical. The alkyl radical can include a cycloaliphatic ring. R is preferably phenyl or an alkyl radical of l to 6 carbon atoms. The reaction is preferably carried out in the presence of an excess of the isocyanate, which also serves as a solvent for the naphthol. In addition, it is desirable to add a small amount of an organic base such as triethylamine to the reaction mixture in order to catalyze carbamate formation. The reaction, which is exothermic, proceeds readily without the external addition of heat. When the reaction mixture is heated to reflux for a brief period, such as about thirty minutes, a nearly quantitative yield of carbamate is obtained. The carbamates can be give 2.1 grams of product. Concentration of the mother liquor afforded an additional 1.0 gram of product. Two recrystallizations of the product from hexane gave white crystals, melting point 100.5-102 C., identified as N- methyl (5,8-dimethyl-5,6,7,8 tetrahydro 1 naphthyl) recovered from the reaction mixture by removing un- 5 carbamate. reacted isocyanate under reduced pressure, followed by The carbamate prepared above was diluted with a 1:1 recrystallization of the residue. solution of acetone and water to a concentration cor- Materials can be protected from attack by insects and responding to one pound of carbamate per 100 gallons nematodes by applying to the material an eiTective amount of diluent. The solution was sprayed on cranberry bean of a carbamate prepared in accordance with the preceding plants which were subsequently infested with Mexican paragraph from a naphthol of this invention. The carbean beetle larvae after the solution had dried on the bamate is applied to the material to be protected in the plants. The solution was also sprayed on English broad form of a pesticidal composition comprising the carbean plants and pea aphid adults, separately, and then bamate and a suitable diluent which forms a fine disper- 1 the aphids were placed on the treated plants. In addition, sion of the carbamate on plants or other materials to be the solution was sprayed on cranberry bean plants infested protected. Suitable solid diluents include talcums, (11- with two-spotted spider mites. A portion of the solution atomaceous earth. Wood fl and silica 3 Wh the Was stripped of acetone, diluted with water to a concendiiuent is a solid, the composition preferably contains tration of 500 p,p,m of carbamate, Combined with 1 from 0.1 to 1.0 weight percent of the carbamate. Suitable percent; by i h f T i X 155 Wetting agent, and liquid diluents include water, acetone, petroleum distilsprayed on sour mash nematodes (Panagreilus redz'vivus). iates and the like. Where the diluent is a liquid, the com- Mortality observations were made three days after treatposition can contain as little as about 0.5 pound of ment. The percent of nematodes killed was estimated by Cafbflmflie P 100 gallons of diluent, he preferred convisual inspection under a microscope. The results are centration being from 0.5 to 2 pounds of carbamate per reported i Table 11 100 allons of diluent. Other pesticidal adjuvants, includi g conventional wetting, dispersing, and emulsifying Examples agents, can also be added to the formulation. The amount Other N-methyl carbamates were prepared following of carbamate deposited on the material can range from the general procedure of Example 13 from certain of the 0.01 to 1.0, preferably 0.1 to 0.5 pound of carbamate other naphthols prepared in Examples 112. These carper square yard of material. No phytotoxicity is shown bamates were similarly tested for pesticidal effectiveness by the carbamates. following the procedure of Example 13, with the excep- The following examples further illustrate the invention that the concentration of the carbamate was equivtion. In each of the examples the reaction products were alent to two pounds of carbamate per 100 gallons of dilidentified by infrared spectrum and nuclear magnetic uent. The results are reported below in Table II. resonance anal 'ses.

i Examples 1 12 TABLE II Derivatives of phenol were cyclialkylated by reaction u u fE iBL E with 1,5-hexadiene in the presence of aluminum phenate, 40 Carbamate MBBL PAM rssM NEM4 Aluminum phenate was prepared in situ by heating a 100 7 35 suspension of the phenol and aluminum to between 150 :83 3 2.3 28 C. and 200 C. until hydrogen evolution had ceased. 1,5- 20 0 hexadiene was then added slowly at a rate such that the -9 v 40 100 5 10 2-1sopropyl 0 10 11.6 5 temperature of the reactlon mlxture did not drop below r new, 4O 0 133 10 160 C. The reaction mixture was held at the indicated v 100 100 67.1 10 temperature for the indicated period of time after Ithe 1Mexicafigeagifgemlarvw addition was completed. The reaction mixture was t en l i a 11 cooled, poured onto a system of ice and hydrochloric acid, extracted with ether and then dried over sodium TABLE I Grams 5,6,7,8-tetra Grams Grams Reaction Reaction hydro-1- alumt- 1,5-hexatemp time, naphtha] Boiling point. num diene hours (yield) C./m1n.iIg 3 it? $313 '2 #1 32 82552 4 51.7 170-170 4 33 -130/02-03 4 51. 7 -135 5 5s 99-103/0. 25 4 51. 7 100-215 a 42 110-114/0. s 3 a 4. 5 200-215 2 55 110113/0. 3 4 51. 7 215-230 2 51 135-115/0. 5 4 51. 7 -130 1. 5 a7 00-05/ 25 4 51.7 170-190 1. 5 :10 turns/0v 25 2 51.7 201x225 12 a7 130-150/0. 7-1.0 2 51. 7 190-210 4 54 120-124/0. e 4-iiuoro 100 2 215.8 -135 3 13 90-109/0. s-1.0

sulfate. The desired 5,8-dimethyl-5,6,7,8-tetrahydro-1- 65 We claim: naphthol was then isolated by distillation. The results 1. A process for preparing 5,8-d1methyl-5,6,7,8-tetobtained are tabulated above in Table I. fahydm'l-naphthols the formula Example 13 One-half ml. of triethylamine was added to a stirred (Jul solution of 3.8 grams of 5,S-dimethyl-5,6,7,8-tetrahydro- 70 l-naphthol and 10 ml. of methyl isocyanate. When the 7 initial reaction had moderated, the solution was heated l to reflux for 15 minutes, cooled, and the excess isocyanate removed under reduced pressure. The viscous oil that y remained was recrystallized front chloroform-hexane to 75 L111:

wherein X and Y independently occupy the 2, 3, or 4 positions and are independently selected from the group consisting of hydrogen, fluorine, chlorine, bromine, lower alkoxy and lower alkyl, which process comprises reacting 1,5-hexadiene with a phenolic reactant having the formula wherein X and Y have the meanings given above, in the presence of aluminum phenate at a temperaure between about 125 C. and about 250 C.

2. The process of claim 1 wherein X or Y is lower alkoxy and the other substituent is hydrogen.

3. The process of claim 1 wherein X or Y is fluorine, chlorine or bromine and the other substituent is hydrogen.

4. The process of claim 1 wherein X or Y is fluorine, chlorine or bromine and the other substituent is a like halogen.

5. The process of claim 1 wherein X or Y is lower alkyl and the other substituent is hydrogen.

6. The process of claim 1 wherein X and Y are lower alkyl.

7. The process of claim 1 wherein the weight ratio of aluminum phenate to 1,5-hexadiene is from about 1:100 to about 110.5.

8. The process of claim 1 wherein the weight ratio of aluminum phenate to 1,5-hexadicne is from about 1:10 to about 1:1.

9. The process of claim 8 wherein the reaction is carried out at a temperature ranging from about 160 C. to about 230 C.

References Cited UNITED STATES PATENTS 2,198,374 4/1940 Bruson et al. 260-619 F 2,553,470 5/1951 Pines et a1 260621 R X 3,267,153 8/1966 Leston 260621 R X FOREIGN PATENTS 1,346,184 11/1963 France 260621 R 776,204 6/1957 Great Britain 260624 C OTHER REFERENCES Bruson et al.: J.A.C.S., vol. 62 (1940), pp. 36-44.

BERNARD HELFIN, Primary Examiner US. Cl. X.R.

260-621 R, 623 R, 624 R 

